The present invention relates to packaging and more particularly to tamper-evident thermoformed packaging.
Thermoformed packaging is used in a wide variety of application. The design and construction of thermoformed packaging typically varies from application to application. One common application for thermoformed packaging is food packaging. For example, fruits and vegetables are now commonly sold in containers made from thermoformed parts. Although food packages may vary in design and construction, one type of common food package includes a thermoformed base and a thermoformed lid that can be closed to cooperatively define an article-receiving space. In some applications, the base and lid are formed from a single portion of thermoplastic material and are joined together along a living hinge. In other applications, the base and lid are separately formed.
The base and lid can be secured together using a variety of different options. For example, the base and lid can be permanently sealed (e.g. welded) together to make it difficult to open and therefore tamper with the content of the package. However, permanently sealed packaging has a number of disadvantages. For example, permanently sealing the package can increase the cost of packaging because it may require the use of relatively expensive sealing equipment (e.g. a welder). Further, consumers have increasingly expressed resistance to the use of permanently sealed thermoformed packaging. Permanently sealed packages can be difficult to open, thereby providing a source of frustration for consumers. As a result of these (and perhaps other) disadvantages, there has been an effort to develop alternative packaging constructions that are not welded or otherwise permanently sealed. Some alternative constructions currently in use include a base and a lid that are snap-fitted together, and can therefore be relatively easily opened and closed.
With food packaging (and some other applications), it can be desirable to provide a mechanism that allows a consumer to determine whether or not the package has been opened. With welded or otherwise permanently-sealed packages, the process of opening the package will typically leave an obvious visual indication that the package has been opened. With other types of packages, such as snap-locked packaging, special accommodations may be needed to provide a visual indication when desired. For example, some conventional food packages include a tear strip that must be removed from a package before it can be opened. Removal of the tear strip leaves an unmistakable visual indication that the package has been opened. Tear strips provide some advantages, but they can increase the overall cost of the package, as well as present difficulties during use.